This proposal for a K23 "Mentored Patient-Oriented Research Career Development Award" will provide the candidate with five years of continuous funding to gain a broad knowledge in the design and conduct of complex clinical oral health trials. This training will enhance the research environment of the Orofacial Pain Center and mentoring capacity of the University of Kentucky College of Dentistry. The candidate earned a PhD in General Medicine from the University of Groningen and received three years of postgraduate graduate training in Orofacial Pain at the University of Kentucky. This award would allow the candidate to evolve to an independent investigator and would prepare the candidate to successfully mentor MS and PhD candidates in orofacial pain research. The training program consists of two phases: a didactic component emphasizing courses in research design, biostatistics, data analysis and epidemiology, and a research phase involving a neuroimaging investigation of central pain processing in patients with chronic face pain. Three specific aims are proposed in this training application: Specific Aim 1. To assess the presence of pain augmentation in patients with chronic masticatory myofascial pain; Specific Aim 2. To investigate differences in location and extent of activation of brain regions involved in trigeminal pain processing between patients with chronic masticatory muscle pain and pain-free volunteers; and Specific Aim 3. To investigate the influence of estrogen level on cerebral activation in response to an acute experimental pain stimulus in patients with chronic masticatory muscle pain and pain-free volunteers. Dr. Charles Carlson, PhD, Professor, Departments of Psychology and Oral Health Science and research director of the Orofacial Pain Center, and Dr. Don Gash, PhD, Alumni Professor and Chair, Department of Anatomy and Neurobiology, and director of the Magnetic Resonance Imaging and Spectroscopy Center, will mentor the candidate. There is limited information on cerebral activation in response to stimulation of trigeminal structures in healthy pain-free volunteers as well as in chronic face pain patients. The available data support that there are important differences in the cerebral processing of pain in chronic pain patients compared to pain-free subjects. Moreover, the existing data suggest that in chronic pain conditions the medial pain system, the structures associated with the processing of the emotional-affective component of pain, exhibits altered activity. Additionally, there is a lack of information about the influence of estrogen on the central processing of pain. The available data suggest that estrogen may have an inhibitory / anxiolytic effect on the perception of pain, possibly by modulating the endogenous opioid system. Because neuroimaging data on this topic are scarce, and chronic pain conditions are predominant in women of reproductive age, the role of estrogen on pain should be further explored.